io6 F. H. KNOWLTON 



of the Trias afford but scanty remains, and it is not until we come 

 to the upper portion, or Rhaetic, that it can really be dignified as a 

 flora. Our North American Triassic flora is believed to belong 

 largely to this portion. Triassic plants have been doubtfully reported 

 from Prince Edward Island, but they are so obviously of Permian 

 types that they may be disregarded. The principal areas are in 

 North Carolina, Virginia, and Pennsylvania, with relatively few in 

 Maryland, New Jersey, Connecticut, and Massachusetts. In the 

 west we have a doubtful plant or two from Wyoming, a considerable 

 number from northern New Mexico, the extensive fossil forests of 

 Arizona, and a very few species from Plumas County, California. 

 Going southward we have small collections from Sonora, from about 

 the City of Mexico, in Honduras, Chile, and western Argentina. In 

 other parts of the world Triassic floras have been found in England, 

 east coast of Greenland, Spitzbergen, North Germany, southern 

 Sweden, Italy, southwestern Spain, Persia, India, China, Tonkin, 

 Japan, New South Wales, New Zealand, and South Africa. 



What, now, are the characters of the Triassic flora ? The domi- 

 nant types of the Paleozoic have largely disappeared. The Lepido- 

 dendrae, Sigillariae, Calamites, Cordaites, Sphenophyllae, and 

 Cycadofilices, so far as ascertained, have all gone, as well as a num- 

 ber of important genera of ferns — Cheilanthites, Mariopteris, Megalop- 

 teris, etc. The most notable survival from the Paleozoic is the 

 so-called Glossopteris flora, which has been found with a few associated 

 forms in Rhaetic rocks at Tonkin, the Stormberg series of South 

 Africa, New South Wales, etc. 



The Triassic flora consists essentially of equisetums, ferns, cycads, 

 and conifers of many genera. A few forms such as Ginkgo, Cla- 

 dophlebis, Thinnjeldia, etc., had a small beginning in the Paleozoic 

 and expanded in the Mesozoic into large groups. But most of the 

 flora is of distinctly Mesozoic and northern origin. 



It has often been said that the plants of the Triassic are depau- 

 perate and pinched in aspect, indicating unfavorable climatic con- 

 ditions. The paleobotanical facts do not altogether bear this out. 

 In North Carolina, Virginia, and Arizona, there are trunks of trees 

 preserved, some of which are 8 feet in diameter and at least 120 feet 

 long, while hundreds are from 2 to 4 feet in diameter. Many of the 



